External radiotherapy is the most common way of giving radiotherapy. It is normally given as a series of short, daily outpatient treatments in the radiotherapy department using equipment similar to a large x-ray machine. Several different types of radiotherapy machines are used to give radiotherapy but they all work in a similar way. One commonly used machine is called a linear accelerator (LINAC).
How many treatments you have will depend on whether the aim is to cure the cancer (curative) or to control its symptoms (palliative).
Curative radiotherapy usually involves having a course of treatments given once a day, often with a rest at the weekends. The treatment may last between 2–7 weeks. Each treatment is called a fraction. Giving the treatment in fractions makes sure that less damage is done to normal cells than to cancer cells. The damage to normal cells is mainly temporary, but this is what causes the side effects of radiotherapy.
Some people may have more than one treatment each day or treatment every day for two weeks, including the weekends. Sometimes treatment may only be given on three days each week – for example, Mondays, Wednesdays and Fridays.
Palliative radiotherapy (for symptom control) may be used in a number of different situations. For example, radiotherapy may be given:
- to one or more bones to help control pain caused by cancer spreading to the bones
- to the lungs to reduce coughing caused by cancer in the lungs
- to help control bleeding caused by lung, bladder or skin tumours.
Palliative radiotherapy may involve only one or two sessions of treatment, but it can involve up to 10 sessions. When treatment is given in one or two sessions, it may cause slightly more short-term side effects, such as flu-like symptoms.